变压器直流偏磁现象研究

发布时间：2018-06-22 00:11

本文选题：变压器 + 直流偏磁　；参考：《西安科技大学》2015年硕士论文

【摘要】：太阳活动引起的地磁暴以及HVDC单极运行方式会引起变压器直流偏磁,直流偏磁会引起变压器铁芯饱和,从而导致变压器噪音增大、振动加剧、局部发热严重,并向电网中输入大量谐波,影响继电保护装置的正确动作等不利影响。因此,研究直流偏磁对变压器的影响及其抑制措施具有重要意义。本文首先对变压器直流偏磁的产生机理进行了详细分析,并就直流偏磁给变压器及电力系统带来诸多不利影响进行了论述。然后利用有限元分析软件Maxwell 2D以单相变压器为例,建立其瞬态电磁场分析模型,分析对比铁芯及铁轭在有不同直流流入情况下的内部磁场变化。根据统一磁耦合电路(UMEC)模型,利用PSCAD/EMTDC仿真分析了不同直流电流作用下,变压器的空载励磁电流波形特征及谐波分析,并比较了单相、三相三柱式及三相五柱式变压器对直流偏磁的耐受能力。最后,以加装补偿绕组及外加直流源补偿法为例,在PSCAD软件中搭建模型并进行仿真计算,分析其抑制效果,并讨论了几种主要抑制直流偏磁措施的优缺点。经过大量仿真分析,得出结论:随着铁芯的饱和,漏磁通逐渐增大,导致漏磁通流过的位置涡流增大,发热量升高,并且铁芯上发热量最高点出现在上下铁轭与铁芯和左右铁轭交接处;三相三柱式变压器耐受直流偏磁的能力最强,单相变压器最弱,三相五柱式变压器的耐受能力介于二者之间;加装补偿绕组及外加直流源补偿方法具有抑制直流偏磁的能力,并且抑制效果明显。
[Abstract]:The geomagnetic storm caused by solar activity and the unipolar operation mode of HVDC will cause DC bias of transformer, and DC bias will cause saturation of transformer core, which will result in the increase of transformer noise, the intensification of vibration and the serious local heating. A large number of harmonics are input into the power network, which affects the correct operation of the relay protection device and other adverse effects. Therefore, it is of great significance to study the influence of DC bias on transformer and its suppression measures. In this paper, the generation mechanism of DC bias of transformer is analyzed in detail, and the adverse effects of DC bias on transformer and power system are discussed. Then the transient electromagnetic field analysis model of single-phase transformer is established by using the finite element analysis software Maxwell 2D, and the internal magnetic field changes of iron core and iron yoke under different DC inflow are analyzed and compared. According to the unified magnetic coupling circuit (UMEC) model, the characteristics of no-load excitation current waveform and harmonic analysis of transformer under different DC current are analyzed by PSCAD / EMTDC simulation, and the single-phase is compared. Three-phase three-column and three-phase five-column transformer to DC bias resistance. Finally, taking the compensation method of adding compensation windings and adding DC source as an example, the model is built in PSCAD software and the simulation calculation is carried out. The restraining effect is analyzed, and the advantages and disadvantages of several main measures to restrain DC bias are discussed. After a lot of simulation analysis, it is concluded that with the saturation of iron core, the flux leakage increases gradually, which leads to the increase of eddy current in the position of flux leakage and the increase of heat. And the highest point of heat generation on the core appears at the junction of the upper and lower iron yoke with the iron core and the left and right iron yoke; the three-phase three-column transformer has the strongest ability to withstand DC bias, while the single-phase transformer is the weakest. The tolerance ability of three-phase five-column transformer is between the two, and the compensation method with compensation winding and external DC source has the ability of restraining DC bias, and the restraining effect is obvious.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM41

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